Burl cutting boards

My experience with pieces like this has only been for turning. To that end, I try to let the wood dry for a couple weeks or months before cutting into it. like any fresh cut greenwood, you want to prevent it from drying too quickly in order to avoid checking and cracking. You can do this by stickering it (placing it on two strips of wood to keep if off the ground and let air circulate below it) in a cool, well-ventilated area, or by sealing the exposed faces with a paraffin wax or latex primer.

In order to use it for a cutting board, you want to make sure the wood isn't too soft or punky and doesn't have crevices for food to collect.

Regarding the value of the rest of the burl, it probably is going to depend on how much someone is willing to pay for it. Several of the catalog retailers like Craft Supplies USA and Woodcraft sell turning blanks. You might take a look at their prices. I used to buy turning blanks for a local retailer and they went for anything from $10 to $150 depending on the size and quality.